1. Field of the Invention
The present invention relates generally to a loudspeaker system, and more particularly to a technique directed at improving the quality of sounds.
2. Brief Description of the Prior Art
In the conventional loudspeaker systems, importance is commonly attached to the enclosure sealing properties.
The reason is that any sound pressure leakage from the enclosure may adversely affect the frequency characteristics.
More specifically, sound waves leaking from the enclosure may interfere with direct sounds from the loudspeaker system and disturb the frequency characteristics. In particular, sound waves leaking from the site apart farther from the loudspeaker system may often have the same sound pressure phases within the interior of the enclosure, resulting in an acute interference.
It is therefore an inviolable rule in typical mounting of the loudspeaker unit on the enclosure baffle to keep the sealing at the mounting surfaces. This mounting is carried out in a textbook manner.
As can be seen in FIGS. 25(A) and 25(B) for example, a loudspeaker unit 1 is mounted such that the internal face of a flange portion 2 at its peripheral portion comes into intimate contact with the front face of a baffle plate 4 of an enclosure 3. Alternatively, the loudspeaker unit 1 is mounted such that the external face of the flange portion 2 comes into intimate contact with the rear face of the baffle plate 4.
In general, the bass characteristics of the loudspeaker system are restricted by the lowest resonance frequency of the loudspeaker unit and the requirement for reproduction of the unit lowest resonance frequency is to impart a sufficient capacity to the unit mounted enclosure. In the conventional loudspeaker systems attaching importance to the enclosure sealing properties, however, the action on the diaphragm of inertial vibrations of the air spring within the enclosure may adversely affect the low-frequency characteristics and transient characteristics of the loudspeaker system. In particular, if the mounting capacity is smaller than the enclosure capacity required by the loudspeaker unit, then the low-frequency characteristics may suffer a remarkable damping.
A loudspeaker unit having a large-diameter diaphragm is suitable for the bass reproduction although use of the large-diameter diaphragm may lead to an increase of the enclosure capacity, rendering an enlargement in dimensions of the loudspeaker system inevitable.
For this reason, the typical loudspeaker system intended for the bass reproduction is apt to add to its size and weight, resulting in high costs and low handling properties.
With a view to solving such deficiencies and reducing the system size, there have been proposed a system using bass reflex, a resonance chamber or an acoustic tube for loading, a seal-up system having sound absorption materials filled into the interior thereof, and a system making corrections based on output detection such as motional feedback and including an electronic circuit such as an equalizer. All of them have however caused any complications in structure, resulting inevitably in a rise of fabrication costs. In such cases, the systems had tendencies of the quality of sounds proper thereto.
Hitherto known as the loudspeaker system cabinet (enclosure) is an R-J cabinet of a type in which as illustrated in FIG. 26 a loudspeaker unit 5 fitted to a supplementary baffle plate 6 is mounted on a baffle plate 8 at the front of a cabinet (enclosure) 7 in a spaced apart manner.
In this R-J cabinet, however, air passages allowing a communication between the interior and exterior of the cabinet 7 open to opposed side ends of an opening 9 of the baffle plate 8, with the result that in spite of its improved bass characteristics the output sound pressure levels in the mid-frequency band will lower with its characteristics having peaks in the vicinity of the bass reproduction limit frequency.
In the past, there has also been proposed a configuration in which a partition is positioned behind the diaphragm spaced by a predetermined distance apart from the diaphragm so as to define an acoustic space therebetween, the inner periphery of the acoustic space leading into the space within the loudspeaker box, the outer periphery of the acoustic space opening to the front face of the loudspeaker box by way of an air vent ring (see Japanese Patent Laid-open Pub. No. Hei2-195796).
This configuration allows the space defined between the partition and the diaphragm to act as a duct for effectively guiding the bass reproduction outputs of the loudspeaker and to enhance the basses since the space at its inner periphery leads into the space within the loudspeaker box and at its outer periphery opens to the front face of the loudspeaker box.
It is however difficult to readily apply this technique to the existing loudspeaker system because the loudspeaker unit itself needs to have an unique specification due to its configuration in which the partition and the air vent ring are integrally mounted on the diaphragm, i.e., the cone to make up the loudspeaker system thereby forming the above space portion.
At the same time, the structure of the cone is also complicated with its increased weight, disadvantageously adding to costs.
Furthermore, due to its bent configuration of the space portion, a smooth radiation of air within the enclosure is not achieved, rendering it difficult to effectively prevent any influence on the diaphragm of the inertial vibrations of the air spring within the interior of the enclosure.
The present invention was conceived in order to solve the conventional problems as set forth hereinabove. It is therefore the object of the present invention to provide a simple improved attachment structure to the baffle plate of the enclosure of the loudspeaker unit to thereby achieve a reduction in size and weight of the loudspeaker system and achieve an enhancement in the low-frequency characteristics and transient characteristics.
In addition to the above object, it is another object to ensure an easy and secure adjustment of the gaps formed along substantially the overall inner perimeter of the opening in the baffle plate between the rear face of the outer peripheral portion of the loudspeaker unit and the front face of the baffle plate, to thereby achieve an enhancement in the bass characteristics and an improvement in the quality of sounds for instance.
The loudspeaker system according to a first aspect of the present invention can satisfy items (1) to (4) which follow.
(1) To enhance the low-frequency band through radiation of resonant sounds within the interior of the enclosure.
(2) To improve the transient characteristics over the full reproduction range to acquire a free, easy and gloomless quality of sounds through the reduction of influences on the diaphragm of inertial vibrations of air springs within the interior of the enclosure.
(3) To achieve more effectively an improvement in the quality of sound through effective reduction of resistance to which the coned paper is subjected as a result of a variation in the air pressure within the interior of the enclosure.
(4) To enhance the bass frequency characteristics and simultaneously prevent any turbulence of characteristics at the other frequencies.
To this end, according to the first aspect of the present invention, there is provided a loudspeaker system including an enclosure and a loudspeaker unit adapted to be fitted to an opening in a baffle plate at the front of the enclosure, wherein around the outer peripheral site of the loudspeaker unit there are formed predetermined air passages which extend along substantially the overall inner perimeter of the opening in the baffle plate, for allowing a communication between the interior and exterior of the enclosure.
It has been found out that in the woofer unit or full-range unit, the optimal value can be conferred on the spatial volume provided equi-angularly between the periphery of the woofer unit frame and the baffle face by use of the spacers at the positions of the unit mounting screws, whereby the optimal spatial volume can serve as a regulator to control the air pressure within the enclosure. Furthermore, the quality of sounds from the sound generator has been improved by fixing the vibration body to the baffle face at several points in place of the surfaces.
The predetermined air passages allowing a communication between the interior and exterior of the enclosure serve as sound holes which through the bass reflex action radiate resonant sounds within the interior of the enclosure to reinforce the bass frequencies.
Influences on the diaphragm of inertial vibrations of the air spring lying within the enclosure are reduced and transient characteristics over the full reproduction range are improved, with the result that a free, easy and gloomless sound quality is obtained.
Furthermore, since the air passages are formed along the outer peripheral site of the loudspeaker unit so as to extend along substantially the overall inner perimeter of the opening in the baffle plate, air can flow in and out uniformly through the outer peripheral site of the loudspeaker unit and the coned paper of the loudspeaker unit can have a gentle curvature toward the air passages, with the result that resistance to which the coned paper may be subjected as a result of a variation in the air pressure within the interior of the enclosure is effectively reduced, achieving an effective improvement in the quality of sounds.
In particular, since the air passages are formed in close vicinity to the loudspeaker unit and along substantially the overall inner perimeter of the opening in the baffle plate, it is possible to enhance the bass frequency characteristics as well as to prevent any turbulences of characteristics at the other frequencies.
In such a case, the loudspeaker unit may be mounted on the baffle plate in such a manner that gaps are defined as the air passages between the rear face of the outer peripheral portion of the loudspeaker unit and the front face of the baffle plate.
Alternatively, the loudspeaker unit may be mounted on the baffle plate in such a manner that gaps are defined as the air passages between the front face of the outer peripheral portion of the loudspeaker unit and the rear face of the baffle plate.
In this case, by way of a plurality of spacers, the gaps may be formed between the internal face of the outer peripheral portion of the loudspeaker unit and the front face of the baffle plate or between the external face of the outer peripheral portion of the loudspeaker unit and the rear face of the baffle plate.
The plurality of spacers may each be in the form of a substantially tubular member, with fittings inserted through the interior of the tubular member being securely fastened to the outer peripheral portion of the loudspeaker unit and to the baffle plate.
In this event, preferably the plurality of spacers are each formed of a material having a predetermined vibration absorptivity.
The plurality of spacers may be formed integrally with the loudspeaker unit or with the baffle plate.
In case of the configuration where the loudspeaker unit is mounted on the baffle plate in such a manner that the gaps are formed as the air passages between the rear face of the peripheral portion of the loudspeaker unit and the front face of the baffle plate, the enclosure may have a top wall portion and a bottom wall portion which are extended forwardly, the enclosure having a pair of right and left support members situated in front of the baffle plate for coupling to the extended portions, with the outer peripheral portion of the loudspeaker unit being fitted to the support members so as to space the outer peripheral portion of the loudspeaker unit apart from the baffle plate, to thereby form the gaps.
Furthermore, the loudspeaker unit may have an attachment protrusion formed integrally with its outer peripheral portion, the attachment protrusion having a plurality of openings which provide the air passages, the attachment protrusion being fitted to the external face or internal face of the baffle plate.
Also, the baffle plate may have an attachment protrusion projecting from the inner peripheral face of the opening, the loudspeaker unit having an attachment protrusion which projects from its outer peripheral face, two the attachment protrusions being coupled together so as to form gaps acting as the air passages between the inner peripheral face of the opening and the outer peripheral portion of the loudspeaker unit.
Incidentally, the enclosure may have a bass reflex port or a bass radiation hole for bass reflex.
In case of the provision of such a bass reflex port by the bass reflex duct or the provision of the bass radiation hole for bass reflex, the peripheral sound pressure can be raised by employing as low a resonance frequency as possible of the bass reflex port or the bass radiation hole.
The loudspeaker system according to a second aspect of the present invention can satisfy items (1) to (4) which follow.
(1) To achieve a reduction in size and weight of the enclosure while simultaneously ensuring an enhanced low-frequency band, a low distortion and a high efficiency.
(2) To provide a loudspeaker system having improved transient characteristics and economic considerations.
(3) To restrain a reduction of the additional mass on the loudspeaker unit diaphragm which may arise from air within the interior of the enclosure, to thereby suppress the damping in the bass reproduction characteristics.
(4) To secure effectiveness in any small-sized loudspeaker systems which are liable to undergo a reduction in the addition mass on the loudspeaker unit diaphragm and which are apt to suffer any damping in the bass reproduction characteristics.
To this end, according to the second aspect of the present invention, there is provided a loudspeaker system including an enclosure and a loudspeaker unit adapted to be fitted to an opening in a baffle plate at the front of the enclosure, wherein the loudspeaker unit is mounted on the baffle plate in such a manner that between the rear face of the outer peripheral portion of the loudspeaker unit and the front face of the baffle plate there are formed gaps acting as predetermined air passages which extend along substantially the overall inner perimeter of the opening in the baffle plate and which allow a communication between the interior and exterior of the enclosure, and wherein said loudspeaker unit has on its outer peripheral portion rear face an annular rim for adjusting confronting areas of the rear face of said outer peripheral portion and of the front face of said baffle plate.
Alternatively, there is also provided a loudspeaker system including an enclosure and a loudspeaker unit adapted to be fitted to an opening in a baffle plate at the front of the enclosure, wherein the loudspeaker unit is mounted on the baffle plate in such a manner that between the front face of the outer peripheral portion of the loudspeaker unit and the rear face of the baffle plate there are formed gaps acting as predetermined air passages which extend along substantially the overall inner perimeter of the opening in the baffle plate and which allow a communication between the interior and exterior of the enclosure, and wherein the loudspeaker unit has on its outer peripheral portion front face an annular rim for adjusting confronting areas of the front face of the outer peripheral portion and of the rear face of the baffle plate.
It has been found out that in the woofer unit or full-range unit, the optimal value can be conferred on the spatial volume provided equi-angularly between the periphery of the woofer unit frame and the baffle face by use of the spacers at the positions of the unit mounting screws, whereby the optimal spatial volume can serve as a regulator to control the air pressure within the enclosure. Furthermore, the quality of sounds from the sound generator has been improved by fixing the vibration body to the baffle face at several points in place of the surfaces.
The predetermined air passages allowing a communication between the interior and exterior of the enclosure serve as sound holes which through the bass reflex action radiate resonant sounds within the interior of the enclosure to reinforce the bass frequencies.
Influences on the diaphragm of inertial vibrations of the air spring lying within the enclosure are reduced and transient characteristics over the full reproduction range are improved, with the result that a free, easy and gloomless sound quality is obtained.
Furthermore, since the air passages are formed along the outer peripheral site of the loudspeaker unit so as to extend along substantially the overall inner perimeter of the opening in the baffle plate, air can flow in and out uniformly through the outer peripheral site of the loudspeaker unit and the coned paper of the loudspeaker unit can have a gentle curvature toward the air passages, with the result that resistance to which the coned paper may be subjected as a result of a variation in the air pressure within the interior of the enclosure is effectively reduced, achieving an effective improvement in the quality of sounds.
Also, since the air passages are formed in close vicinity to the loudspeaker unit and along substantially the overall inner perimeter of the opening in the baffle plate, it is possible to enhance the bass frequency characteristics as well as to prevent any turbulences of characteristics at the other frequencies.
Then, for a bass loudspeaker including a flame rib which acts as the fitting surface to the baffle plate but has no even annular shape or including a small fitting surface area wherein it may be difficult to regulate the gaps formed along substantially the overall inner perimeter of the baffle plate opening between the rear face of the outer peripheral portion of the loudspeaker unit and the front face of the baffle plate, a large-diameter annular rim is mounted on the front face or rear face of the outer peripheral portion of the loudspeaker unit so as to increase the confronting areas of the rear face or front face of the outer peripheral portion and of the front face or rear face of the baffle plate, whereby there can easily be achieved an enhancement in the low-frequency characteristics and an improvement in the quality of sounds over the full range.
In the mid-frequency sound loudspeaker system and the high-frequency sound loudspeaker system, for the purpose of improving the auditory localization of image sounds through the radiation of sounds within the enclosure from the periphery thereof, a large-diameter annular rim is mounted on the rear face or front face of the outer peripheral portion of the loudspeaker unit so as to increase the confronting areas of both the rear face or the front face of the outer peripheral portion of the loudspeaker unit and the front face or the rear face of the baffle plate, thereby making it possible to prevent the low-frequency characteristics from being degraded.
In such a case, in the configuration where the annular rim is provided on the rear face of the outer peripheral portion of the loudspeaker unit, the loudspeaker unit may have on its outer peripheral portion an annular rim portion located at the rear face of the outer peripheral portion, a plurality of spacer portions projecting backward from the rear face of the annular rim portion, and a ring-like rib portion positioned behind the rear face of the annular rim portion for coupling the plurality of spacers to one another, the rim portion, the plurality of spacer portions and the rib portion being integrally formed with the outer peripheral portion of the loudspeaker unit, the rib portion being fitted to the front face of the baffle plate.
In case of providing the annular rim on the external peripheral portion front face of the loudspeaker unit, the loudspeaker unit may have on its outer peripheral portion an annular rim portion located at the front face of the outer peripheral portion, a plurality of spacer portions projecting forward from the front face of the annular rim portion, and a ring-like rib portion positioned in front of the front face of the annular rim portion for coupling the plurality of spacers to one another, the rim portion, the plurality of spacer portions and the rib portion being integrally formed with the outer peripheral portion of the loudspeaker unit, the rib portion being fitted to the rear face of the baffle plate.
By virtue of the structure where the annular rim and spacers are previously formed integrally with the loudspeaker unit itself in this manner, the number of parts of the apparatus can totally be reduced. Application of the present invention to any loudspeaker systems will thus become possible by the attachment of only the loudspeaker unit, contributing to fabrication easiness.